In semiconductor devices, strain engineering has been applied to improve electron/hole mobility.
A contemporary method for forming stressors inside a semiconductor material usually requires an ion implantation mask, which further requires a photolithography process, so as to control lateral locations of stressors to be formed. In such a method, individual, independent control of the stressors including the relative locations, depths, sizes, and doped concentrations thereof are not available, because the stressors are formed simultaneously by the same implantation. Control of the depth of the stressor from the surface (e.g., a top surface of the substrate) is currently performed by changing accelerating voltage of the ion beam used to form the strainer. The problem with changing accelerating voltage of the ion beam is that the throughput can be delayed because of the machine stabilization time.